Mineral oil composition



Patented Mar. 21,1939 v k umrso STATES.- PATENT, orrlce 2,151,300 )7 MINERAL OIL COMPOSITION No Drawing. Application December 16, 1938, v Serial No. 246,244

This invention has to do in a. general way 1 indicated above, have proved to be highly effec- -'with mineral oil compositionsand is more partive in improving certain properties of mineral ticularly related to mineral oil compositions of lubricating oils, they have one disadvantage in the lubricant type to which an agent has been that an oil containing an ester of phosphorous 5 added for the purpose of improving the oil in acid or an organic phosphite tends to stain metal 6 en respects. The present application is a containers, particularly tin-coated metal concontinuation in part of our copending applicatainers, when stored therein at atmospheric temtlon Serial No. 158,738, filed August 12, 1937. perature. With increase in temperatures this It is the object of this invention to' provide a staining becomes accelerated. Thus an S. A. E.

10; novel class of improving agents for'use in min- 20 motor oil containing 0.25 per cent of tri-terl0 eral oil fractions of the class described and furtiary amyl phenyl phosphite will cause a visible ther to provide improved mineral .oil composistain in a. tin-coated container in about twentytions containing such improving agents. one days when stored at 120 F. and in about Asis well known to those familiar with thethree days when stored at 160 F. art, modern practice in the manufacture of lu- The effect of customer reaction when discovl5 bricants requires the addition of various agents -ering such staining is obvious, particularly when to the mineral oil base stocks for the purpose of much motor oil is sold in containers intended adding new properties, improving inherent propfor re-use by the customer for other purposes.

erties, or inhibiting the development of unde- Of more actual'importance is the fact that the sirable properties latently present within the oil. staining is accompanied by a darkening of the oil. 20 It is customary, for example, where the lubricant I which is also highly objectionable from a maris to be subjected to extremely high bearing keting standpoint. Furthermore, the unit of pressures, such as are encountered in hypoid effectivenes of the oil with respect to the purgears, to add an agent which will increase the pose for which the ester of phosphorous acid is load-carrying capacity of the oil. Such agents added .is decidedly impaired, since the staining 25 are known as extreme pressure or E.- P. agents. of the t -coated container and the darkening It is also customary where the oil is to be used of the oil are the results of deterioration of the under oxidizing conditions as in an automobile r ester of phosphorous acid. crank case to add an agent which will inhibit Since all known esters of phosphorous acid or the deleterious effects of ondation on the oil. organic phosphites are inherently unstable, par-- 30 In this latter regard it has been found that moticularly in the presence of moisture and more tor oil compositions, particularly those prepared particularly in the presence of acids or alkalies, from crude oil fractions of high paraflinicity or it is obvious that the serious objections to such from oils which have been solventerefined, when esters or phosphites,for improving certain char- 5 used in engines employingbearing surfaces of acteristics of mineral oils, particularly motor oils, cadmium-silver, copper-lead,high-lead babbitts cannot beovercome without'improving the inand similar alloys are prone to cause corrosion herentstability of the esters. This inventionis of such bearings. This apparently arises from specifically directed to the solution of this probthe formation of acidic reaction or oxidation lem and is predicated upon the discovery that 40 products under the conditions of use. Additive "the stability of esters of phosphorous acid, par- 40 agents which when added to theoil prevent such ticularly when used in small concentrations as corrosive action fall into the general class of improving agents for mineral oils, can be dematerials known as oxidation inhibitors or anticidedly increased by means of a relatively small oxidants and may be more specifically classified proportion of an oil-soluble organic amine.

as corrosion inhibitors. Our invention, therefore, contemplates as an Among the more successful compounds which improving agent for mineral oils a composition have been developed for use as corrosion incomprising anorganic phosphite or ester of phoshibitors are the esters of phosphorous acid, which phorous acid and an oil-soluble organic amine we may also term organic phosphites. Besides I in sufli'cient amount to stabilize the ester or-phos- 5o functioning as corrosion inhibitors or antioxiphite against deterioration or hydrolysis when dants in mineral oil fractions refined'for motor added to the, oil; It will be seen that with such lubricants and the like, these compounds also a composition the ester is protected against 'defind use as extreme pressure agents in lubricants terioration both prior to and after its addition for hypoid gears, etc. to the oil. It will be understoodhowever, that Although the esters of phosphorous acid, as the organic phosphite-and the amine may be 55 added to the oil separately, and our invention therefore contemplates a mineral oil composition containing an ester of phosphorous acid in sufficient amount to stabilize the 011 against the deleterious effects of oxidation (such as corrosion of alloy bearings, 'etc.) or in sufficient amount to impart extreme pressure characteristics to the oil and an oil-soluble organic amine in sufiicient amount to bring about substantial stability and retard staining action of the phosphorous acid ester upon tin-coated containers.

Broadly, therefore, it will be seen that our invention comprehends two essential constituents. namely, an organic phosphite and an oil-soluble organic amine, which may be blended together in suitable proportions and added to the oil as a compounded oil-improving agent or which may be independently added to the. oil in the required proportions to give in both events an improved mineral oil composition.

The organic phosphites or esters of phosphorous acid contemplated by this invention may be represented as a class by the general formula:

rv-x

n x r' RX/ in which R represents an aryl or an alkyl radical; R represents hydrogen, aryl, or allqyl radicals; and}! represents oxygen or sulfur. The

term aryl as employed herein is inclusive of unsubstituted aromatic hydrocarbon radicals and aromatic hydrocarbon radicals in which one or more nuclear hydrogen atoms ave been substituted with an aliphatic hydrocarbon group, for example,

Within the general class of organic phosphites discussed above, preference is given to thetriesters of phosphorous acid, both aryl and alkyl. Illustrative of the triaryl phosphites may be mentioned triphenyl phosphite, tri-tertiary amyl phenyl phosphite, tritertiary butyl phenyl phos-.

phite, tricresyl phosphite, tribeta naphthyl phosphite, etc. Illustrative of trialkyl phosphites are tributyl phosphite, tri-iosamyl phosphite, etc.

Although preference is given to 'triesters of phos- 'phorous acid of the type represented by the foregoing examples, it is again emphasized that our invention is not restricted thereto but encompasses phosphites (including thiophosphites) as a general class.

'As to the amine constituent of the oil-improving agent and improved mineral oil composition contemplated herein,- preference is given to the cyclohexylamines (dland mono-), dicycloheiwlamine being particularly preferred. The invenaniline, diamylamine, and hexamethylenetetra-.

amine. Other-amines of somewhat less effectiveness are tetramethyl thiuram disulflde, paraphenetidine, ethyl alphanaphthylamine, orthoaminodiphenyl, ortho-amino-phenol, methyl anthranilic acid, dibeta naphthylamine, and

para-nitraniline.

The range of proportions of the organic phosphite and the amine which may be employed in compounding the mineral oil-improving agents or which may be added to a mineral oil independently to provide the improved mineral oil compositions contemplated herein may be varied over relatively wide limits. We may employ, for example, equal parts of the phosphite and the amine, or the amount by weight of amine used may be as little as 0.25 per cent of that of the phosphite. Where the phosphite is to' be used for the purpose of inhibiting corrosion in a motor lubricant it appears that an amount of amine in excess of about 50 per cent the weight of the phosphite is likely to affect the corrosion-inhibiting power of the phosphite, and for such use it is therefore preferable to use the amine in amounts not exceeding 50 per cent the weight of the phosphite used. For general purposes the quantity of amine may be varied from about 0.4 per cent to about 20 per cent the weight of the phosphite (or from about 0.001 per cent to about .05 per cent the weight of the oil), with proportions of from about 0.4 per cent to about four per cent (from about .001 per cent to about .01 per cent based on the oil) considered as preferred Very satisfactory corrosion inhibiting compositions are obtained with phosphite of the type disclosed herein, such as tritertiary amyl phenyl phosphite or tritertiary butyl phenyl'phosphite,

for example, containing from about 2 per cent to about 3 per cent of a cyclohexylamine, preferably the dicyclohexylamine. It will be understood, of course, that the'solubility of a particular amine in mineral oil is a factor which must be considered in determining the quantity of that amine used in the oil and, consequently, also affects the quantity which will be employed in a ghosphite and amine composition for usein the The quantity of the composite organic phosphite and amine inhibiting agent added to the oil or the combined percentage of phosphite and amine independently added to theoil may also be varied over relatively wide limits, depending upon .the oil, the proportions of phosphite and amine used, and the purpose forwhich the improving agent is added. In general it appears that satisfactory results'will be obtained-in inhibiting the corrosive action of motor lubricants with the use of a combined amount of phosphite and amine equal 'to from about 0.1 per cent to about 5 per cent the weight of ti oil.

An interesting observation which we have made regarding the combined use of an organic phosphite and an amine is that the improved results obtained are apparently not due to any antioxidant aefiect of the amines added, since many of the most effective amines, particularly cyclohexylamine, are not effective antioxidants ac? cording to tests commonly used for determining antioxidant ability of additive compounds in oil.

The following examples constitute specific illustrations of the invention contemplated herein and will serve to amplify the generalizations made hereinabove. v

Exnnnn 1 per cent of these same phosphites and 0.05 per cent or less (based on the oil) of various amines and subjected to the same test, and in no case was any staining discernible at the end of 104 days of storage when the test was discontinued. The following representative amines were used in this series of tests: (1) cyclohexylamine, (2) dicyclohexylamine, (3) lecithin, (4) morpholine, (5) orthotoluidine, (6) triethanolamlne, (7) triethanolamine stearate, (8) paraphenylene diamine, (9) paratoluidine, (10) beta naphthylamine, (l1) dianisidine, (12) orthotolidine, (13) para,para-diamino-diphenyl methane, (14) phenylhydrazine, (15) amylamine, (16) aniline, (17) diamylamine, and (18) hexamethylenetetramine. Other amines somewhat less eflective under the same conditions for the purpose than the foregoing are the following:

The mineral oil compositions used in the foregoing tests contained, as stated above, 0.25 per cent of the organic phosphite and 0.05 per cent or less (depending upon solubility) of the organic amine. These mineral oil compositions may be formed by adding the phosphite and the amine to the oil independently, but it is preferable to have the phosphite and the amine previously blended as a mineral oil-improving agent, thus safeguarding against deterioration of the phosphite prior to its incorporation in the oil. Composite mineral oil-improving agents to form oil blends of the foregoing types would consist of about 100 parts by weight of the phosphite and 20 parts or less of the amine, the improving agent being added to the oil in amounts of about .30 per cent or less, depending upon the amine content.

EXAMPLE 2 As mentioned above, cyclohexylamine, orthotoluidine, and triethanolamine were among the most eflective stabilizers observed. 'In order to differentiate between these compounds the storage temperature was raised to 160 F. and the following results were then obtained in a twentyone day test period, using as a base oil an S. A. E

20 oil. The phosphite used in this test was tripara-tertiary amyl phenyl phosphite. In Table 11 below the three amines tested are indicated as follows: Cyc. (cyclohexylamine), Ort. (orthotoluidine), and Triet. (triethanolamine). Under the heading Per cent concentration in oil are indicated the concentration of the phosphite (Pho.), the concentration of the amine Table 11 Pro rtions Pei-cant ofilnoflntraii! pro;-

on o Storage at 160 F., I m results Pho Am I A. Pho. Am.

0.25 0.01 0.26 4.0 No stain (21 days). 0. 25 0. 005 0. 255 100 2. 0 No stain (21 days). 0. 25 0. 001 0. 251 100 0. 4 Stain (21 days) 0. 25 0.01 0.26 100- 4. 0 Stain (3 days). 0.25 0.005- 0. 255 100 2.0 Stain (3 days). 0.25 0. 001 0.251 100 0.4 Stain 3 days). 0. 25 0. 01 0. 25 100 4. 0 Stain (6 days) 0.25 0.005 0.255 100 2.0 Stain (5 days) 0. 25 0.001 0. 251 100 0. 4 Stain (3 daysg. 0. 25 100 0.0 Stain (3 days Enron: 3

It has been mentioned above that the deterioration of an ester of phosphorous acid in a motor oil, for instance, is accompanied by a darkening of the oil as well as by staining ii the oil is stored in a metal container, particularly a tin-coated container, where it is easily visible by contrast. The effectiveness of cyclohexylamine for stabilizing an ester of phosphorous acid in an oil against such deterioration and its accompanying effect upon darkening of the'oil is shown by the data in Table III below in which the "phosphite" was tripara-tertiary amyl phenyl phosphite and in which the amine" was cyclohexylamine.

Table III Color after 21 days storage Oil blend at 160 F. in

tinned container Loribond S. A. E. 20 oil+0. phosphltc.. S. A. E. 20 oilI0.25 phosphiteand 0.017 amine 100 S. A. E. 20 all 0.25 0 phosphite and 0.005 amine. 105

EXAHPLE 4 As has been previously pointed out, all known esters of phosphorous acid or organic phosphites are inherently unstable and our invention contemplates any suitable compound from this whole class as one constituent of the oil-improving agent or the improved'mineral oil composition. Other representative phosphites which may be used are the alkyl phosphites, particularly the trialkyl phosphites, ,of which tributyl phosphite and triamyl phosphite are representative examples. The stain inhibiting action of amines on alkyl phosphites is demonstrated by Table IV below, which shows the results of a -160 F. storagetest on S. A. E. 20 motor oil, using dicyclohexylamine (Dicyc.) as the amine and tri-isoamyl phosphite as the phosphite (Alk. Pho.). The various headings in the table have the same significance as in Table II.

Table IV Percent concen- 2 5 522 tioninoil in gage! Storage at F Amine results Alk. Alk.

mm Am. I. A. phm Am.

a... 0.25 .25 100 0.0 Stain (a days). Dicyc 0.25 0.015 .265 100 0.0 No stain (6 days).

Exauru 5 The term organic phosphite used herein, as f we have previously stated, is intended to be inclusive of thiophosphites. The stain-inhibiting action of amines upon the thiophosphites isdemonstrated by Table V below, which shows the results of a storage test at l50-160 F. on S. A. E. 2 0 motor oil, using dicyclohexylamine (Dicyc.) as the amine and triphenyl trithiophosphite (Thiophos.) as the phosphite. The various headings in the table have the same significance as in Table II.

It is to be understood that while .we have herein given certain speclficexamples of phosphites and amines, such examples are for illustration only. The invention is not limited to any particular phosphite or, amine or to any particular combinations of phosphites and amines but includes within its scope such variations and modifications as fairly come within the spirit-of the appended claims.

We claim:

l. A'lubricating oil composition comprising a major proportion of a mineral lubricating oil, a minor proportion of an ester of phosphorous acid, which would normally tend to stain tin-coated metal containers, and a small amount, suflicient to bring about substantial stability of said ester and retard such staining action, ofan oil-soluble organic amine.

2. A lubricating oil composition comprising a major proportion of a mineral lubricating oil, a minor proportion oi an ester of, phosphorous acid, which would normally tend to stain tin-coated metal containers, and a small amount, suflicient to bring about substantial stability of said ester and retard such staining action, of a material selected from the group consisting of cyclohexylamine; dicyclohexylamine; lecithin; morpholine;

orthotoluidine; triethanolamine, triethanolamine stearate; para-phenylene diamine; paratoluidine; beta naphthylamine; dianisidine; orthotolidine; para,para-diamino diphenylmethane; phenyl hydrazine; amylamine; aniline; diamylamlne; and hexamethylenetetramine.

3. A lubricating oil composition comprising a major proportion of a mineral lubricating oil, a minor proportion of an ester of phosphorous acid, which would normally tend to stain tincoated metal containers, and a small amount, suflicient to bring about substantial stability of said ester and retard such staining action, of a cyclohexylamine;

4. A lubricating oil composition stable against deterioration when stored in tin-coated containers comprising a major proportion of mineral lubricating oil, a minor proportion of an ester of phosphorous acid,which normally tends to stain such containers, and not more than about 0.05 per cent by weight 01 an oil-soluble organic amine.

5. A lubricating oil composition, stable against deterioration when stored in tin-coated containers, comprising a major proportion of mineral lubricating oil, a minor proportion of an aryl phosphite, and not more than 0.05 per cent by weight of an oil-soluble organic amine.

lubricating oil, a minor proportion of an alkyl phosphite, and not more than 0.05 per cent by weight of an oil-soluble organic amine.

7. A lubricating oil composition stable against deterioration when stored in tin-coated containers comprising a major proportion of a mineral lubricating'oil, a minor proportion of an organic phosphite, and not more than 0.05 per cent by weight of a cyclohexylamine.

8. A lubricating oil composition comprising a major proportion of a mineral lubricating oil, a minor proportion of a triaryl phosphite, and from 0.001 to 0.01 per cent of a cyclohexylamine.

9. A lubricating oil composition comprising a major proportion of a minerallubricating oil, a minor proportion of a triester of phosphorous acid and a small amount, suflicient to bring about substantial stability of the said triester, of an oil-soluble organic amine.

10. A lubricating oil composition comprising a major proportion of a mineral lubricating oil, a minor proportion of a triester of phosphorous acid and a small amount, sufficient to bring about substantial stability of the said triester, of an oil-soluble organic amine selected from the group consisting of cyclohexylamine; dlcyclohexylamine; lecithin; morpholine; orthotoluidine; triethanolamine; triethanolamine stearate; paraphenylene dlamine; para-toluidine; beta naphthylamine; dianisidine; orthotolidine; para,paradiamino diphenyl methane; phenyl hydrazine; amyl amine; aniline; dia'mylamine; hexamethylenetetramine. l

11. A lubricating oil composition comprising: a major proportion oi a mineral lubricating oil; a minor proportion of an organic phosphite selected from the group consisting of triamylphenyl phosphite, tributyl phenyl phosphite,

triphenyl phosphite, tricresyl phosphite, tributyl phosphite, and triamyl phosphite, and a small amount, sufllcient to bring about substantial stability of the phosphorus compound, of an oilsoluble organic amine.

12. A lubricating oil composition comprising: a major proportion of a mineral'lubricating oil; a minor proportion of an organic phosphite selected from the group consisting of triamyl-phenyl orthotoluidine, triethanolamine, triethanolamlne stearate, para-phenylene diamine, para-toluidine, beta naphthylamine, dianisidine, orthotolidine, para,para-diamino diphenylmethane, phenyl hydrazine, anylamine, aniline, diamylamine, hexamethylenetetramine.

13. A lubricating oil composition comprising: a major proportion of a mineral lubricating oil; a minor proportion of a phosphorus compound selected from the group consisting of triamylphenyl phosphite, tributyl phenyl phosphite, tricresyl phosphite, triphenyl phosphite, tributyl phosphite, and triamyl phosphite; and a small amount, suflicient to bring about substantial stability of the phosphorus compound, of a cyclohexylamine.

14. An improving'agent for mineral oils and the like comprising an ester or phosphorous acid and in admixture therewith an oil-soluble organic amine in an amount from about 0.25 per cent to about 50 per cent of the weight of said ester.

15. An improving agent for mineral oils and the like comprising an ester of phosphorous acid and in admixture therewith an oil-soluble organic amine in an amount from about 0.4 per cent to about 20 per cent the weight of said ester.

16. An improving agent for mineral oils and the like comprising an ester of phosphorous acid and in admixture therewith an oil-soluble organic amine in an amount from about 0.4 per cent to about 4.0 per cent the weight of said'ester.

17. An improving agent for mineral oils and the like comprising an ester of phosphorous acid and in admixture therewith from about two to about three per cent by weight of a cyclohexylamine.

18. An improving agent for mineral oils and the likeoomprising a triester of phosphorous acid and in admixture therewith from about 0.4 per cent to about 20 per cent by weight of an oilsoluble organic amine.

19. An improving agent for mineral oils and the like comprising an organic phosphite selected from the group consisting of triphenyl phosphite,

' from the group consisting of triphenyl phosphite,

tricresyl phosphite, triamyl phenyl phwphite, tributyl phenyl phosphite, triamyl phosphite, and tributyl phosphite and in admixture therewith from about two per cent to about three per cent by weight of a cyclohexylamine.

. ROBERT C. MORAN.

mm P. KOZACIK. a 

